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2.
Nutrients ; 11(10)2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31618910

RESUMO

The central and peripheral effects of caffeine remain debatable. We verified whether increases in endurance performance after caffeine ingestion occurred together with changes in primary motor cortex (MC) and prefrontal cortex (PFC) activation, neuromuscular efficiency (NME), and electroencephalography-electromyography coherence (EEG-EMG coherence). Twelve participants performed a time-to-task failure isometric contraction at 70% of the maximal voluntary contraction after ingesting 5 mg/kg of caffeine (CAF) or placebo (PLA), in a crossover and counterbalanced design. MC (Cz) and PFC (Fp1) EEG alpha wave and vastus lateralis (VL) muscle EMG were recorded throughout the exercise. EEG-EMG coherence was calculated through the magnitude squared coherence analysis in MC EEG gamma-wave (CI > 0.0058). Moreover, NME was obtained as the force-VL EMG ratio. When compared to PLA, CAF improved the time to task failure (p = 0.003, d = 0.75), but reduced activation in MC and PFC throughout the exercise (p = 0.027, d = 1.01 and p = 0.045, d = 0.95, respectively). Neither NME (p = 0.802, d = 0.34) nor EEG-EMG coherence (p = 0.628, d = 0.21) was different between CAF and PLA. The results suggest that CAF improved muscular performance through a modified central nervous system (CNS) response rather than through alterations in peripheral muscle or central-peripheral coupling.

3.
Rev. bras. ativ. fís. saúde ; 24: 1-7, out. 2019.
Artigo em Português | LILACS | ID: biblio-1047135

RESUMO

A prescrição da intensidade do exercício de forma autosselecionada em função de maior afeto positivo é uma estratégia utilizada para promover aderência da população na prática de exercícios. Entre-tanto, ainda não foram investigadas as implicações que essa estratégia pode gerar na valência afetiva de idosos em ambientes não laboratoriais e em aulas em grupos. O objetivo desse estudo foi analisar se o exercício com intensidade autosselecionada realizado em grupos de idosos pode influenciar na valência afetiva. A amostra foi composta por 176 idosos, sendo 42 homens, com média de idade 70,70 ± 10,10 anos e 134 mulheres, com média de idade 71,00 ± 6,60 anos. Os idosos vinculados a um centro comunitário reportaram a valência afetiva e percepção subjetiva de esforço após uma caminhada de 30 minutos com intensidade autosselecionada. Os participantes foram alocados em três grupos segundo os tercis de percepção subjetiva de esforço: grupo com baixa (GBPE), média (GMPE) e alta (GAPE) percepção de esforço. Foi identificado que todos grupos se diferenciam entre si na valência afetiva [c² (2) = 50,860; p < 0,05]. A magnitude das diferenças pelo tamanho de efeito foi moderada na análise global (*ES = 0,331) e entre GBPE e GAPE (ES = 0,329). Conclui-se existe uma implicação negativa na valência afetiva em exercício com autosseleção da intensidade rea-lizados por idosos em grupos comunitários, possivelmente causado por fatores psicossociais capazes de influenciar na variabilidade de respostas perceptivas


The self-selected exercise intensity prescription due to greater positive affect is a strategy used to promote adherence of the population to exercise. However, the implications that this strategy may have on the affective valence of the elderly in non-laboratory environments and in group classes have not still investigated. The purpose of this study was to analyze whether self-selected intensity exercise performed in elderly groups can influence affective valence. The sample consisted of 176 elderly, 42 men, with a mean age of 70.70 ± 10.10 years and 134 women, with a mean age of 71.00 ± 6.60 years. The elderly linked to a community center reported affective valence and rating perceived exertion after a 30-minute walk with self-selected intensity. Participants were allocated to three groups according to the terciles of rating perceived exertion: group with low (GBPE), medium (GMPE) and high (GAPE) perceived exertion. It was identified that all groups differ in affective valence [c² (2) = 50,860; p <0.05]. The magnitude of the differences by effect size was moderate in the overall analysis (*ES = 0.331) and between GBPE and GAPE (ES = 0.329). In conclusion, there is a negative implication in affective valence in self-selected exercise intensity performed by the elderly in community groups, possibly caused by psychosocial factors capable of influencing the variability of perceptual responses


Assuntos
Saúde do Idoso , Caminhada , Afeto
4.
Int J Sports Med ; 40(12): 774-778, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31476784

RESUMO

We compared results of Special Judo Fitness Test (SJFT) performance of young athletes of two different age categories after correcting body mass (BM) variations by allometric scales. Thirty young judokas (14.2±3.6 years) belonging to two age categories underwent an SJFT: under 15 (U15) years old (12.1±2.4 years; 46.5±15.6 kg; 152.4±11.2 cm) and under 21 years old (U21) (18.2±0.8 years; 77.1±23.5 kg; 174.2±8.9 cm). Allometric exponents of -0.33 and 0.67 were used to correct the influence of BM variations on SJFT performance results. After correction using the -0.33 exponent, U21 showed a higher number of throws (TNT) than U15 (85.5±9.9 and 68.8±12.0, p<0.05, respectively), although the SJFT index had been similar between these groups (67.3±10.1 and 61.7±8.1, p>0.05, respectively). In contrast, TNT normalized by the 0.67 exponent was higher in U15 than U21 (1.55±0.29 and 1.17 ± 0.25, p<0.05, respectively). Likewise, the SJFT index was higher in U15 than in U21 when using the same exponent (1.55±0.29 and 1.17±0.25, p<0.05, respectively). In conclusion, the -0.33 exponent may be useful to remove the influence of BM variations, thus discriminating SJFT performance results in U15 and U21 judokas. Moreover, the 0.67 exponent may overestimate SJFT indices in low-age judokas.


Assuntos
Desempenho Atlético/fisiologia , Índice de Massa Corporal , Teste de Esforço/métodos , Artes Marciais/fisiologia , Aptidão Física/fisiologia , Adolescente , Criança , Feminino , Humanos , Masculino , Adulto Jovem
5.
Physiol Behav ; 208: 112580, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31220517

RESUMO

BACKGROUND: Studies have shown a relationship between prefrontal cortex (PFC) activation asymmetry and psychological responses to exercise, so that a higher rest activation in left rather than right PFC has been associated with positive psychological responses to exercise such as an improved affect, anxiety and multidimensional arousal states. PURPOSE: To review: 1) evidence that PFC activation asymmetry before exercise is associated with psychological responses to exercise; 2) protocols of PFC asymmetry determination. METHODS: A systematic review (SR) was performed on studies retrieved from the PubMed and Web of Science database up to 04-30-2019. Eligibility criteria were: 1) studies investigating participants submitted to aerobic exercises; 2) including cerebral activation measures through electroencephalography (EEG) before the exercise bout; 3) and psychological measures during or after the exercise bout; 4) original studies. RESULTS: A number of 1901 studies was retrieved from the databases and 1 study was manually inserted. Thereafter, 1858 studies were excluded during the screening stage so that 30 studies remained for the SR. After full reading, 22 studies were excluded and 8 studies composed the final SR. Methodological assessment revealed that 62.5% of the studies showed a low risk of bias, while 34.37% and 3.12% showed either an unclear or a high risk of bias, respectively. Protocols of PFC activation asymmetry used EEG at F3-F4-P3-P4 (3 studies), F3-F4 (2 studies), F3-F4-T3-T4 (1 study), F3-F4-F7-F8-T5-T6-P3-P4 (1 study) and Fp1-Fp2-Fz-F3-F4-F7-F8-Cz-C3-C4-T3-T4-T5-T6-Pz-P3-P4-Oz-O1-O2 (1 study) positions. Most studies (75%) found a higher left PFC activation associated with a greater affect (n = 2), energetic arousal (n = 2), lower anxiety (n = 2) as well as calmness and tired arousal, simultaneously (n = 1). CONCLUSIONS: Although the heterogeneity of PFC asymmetry protocols, reviewed studies showed a low risk of bias, suggesting that a higher left PFC activation is associated with a positive psychological response to exercise.

6.
Rev. bras. ciênc. mov ; 27(2): 218-224, abr.-jun.2019.
Artigo em Inglês | LILACS | ID: biblio-1009815

RESUMO

Music can be considered as an ergogenic aid of psychological nature. Currently, athletes of different training status regularly use music as an ergogenic aid to improve performance in different exercise models in their training sessions. In order to understand the effect of music on psychophysiological responses to physical exercise, a music-oriented search was performed on the Pubmed and Web of Science databases to select relevant articles to this theme, thus enabling to present a critical review to explain the three main suggested ergogenic mechanisms of music: 1) Music and perceptive responses during exercise; 2) Influence of music on exercise in different intensities; 3) Action of music on the central nervous system. One of the reasons to listening to music during training sessions is the strong motivational factor during the practice of physical activity. Studies have pointed out benefits such as an improved mood, excitatory control, reduced subjective perception of effort, increased motivation and improved physical performance. In this sense, although the real mechanisms that lead music to be considered as an ergogenic aid to improve performance remain unknown, music seems to have important effects on psychological responses generated in the central nervous system, thus acting as a stimulating agent for the release of excitatory neurotransmitters such as serotonin and endorphin. On the other hand, according to the theory of parallel processing / dissociation, the main mechanism of music to improve physical performance is the increased dissociative thoughts to exercise, thereby reducing perceptual responses processed through the brain that result in increased positive emotional responses to exercise....(AU)


A música pode ser considerada como um recurso ergogênico de natureza psicológica. Atualmente, atletas de diferentes níveis de treinamento utilizam a música como um recurso ergogênico em suas sessões de treinamento em diferentes modelos de exercício para melhorar o desempenho. Para entender o efeito da música nas respostas psicofisiológicas no desempenho físico foi realizada uma busca intencional nas bases de dados 'Pubmed' e 'Web of Science' de artigos relevantes ao tema, desse modo, a presente revisão foi conduzida de maneira crítica para explanar os principais mecanismos sugeridos para a ação ergogênica da música em 3 tópicos: 1) Músicas e respostas perceptivas durante o exercício; 2) Influência da música sobre o exercício em diferentes intensidades; 3) Ação da música sobre o sistema nervoso central. Um dos motivos da utilização da música durante as sessões de treinamento é o forte fator motivacional durante a prática da atividade física. Estudos apontam alguns benefícios como a melhora do humor, controle excitatório, redução da percepção subjetiva de esforço, aumento da motivação e melhora do desempenho físico. Nesse sentido, embora os reais mecanismos que levam a música a ser considerada um recurso ergogênico ainda permanecem desconhecidos, a música parece ter importantes efeitos sobre as respostas psicológicas geradas no sistema nervoso central, atuando como um agente estimulante para a liberação de neurotransmissores excitatórios como a serotonina e endorfina. Por outro lado, de acordo com a teoria do processamento paralelo/dissociação, o principal mecanismo da música sobre o desempenho físico é o aumento da dissociação durante o exercício, reduzindo as respostas perceptivas processadas no cérebro, com a resultante do aumento de respostas emocionais positivas ao longo da tarefa....(AU)


Assuntos
Exercício , Sistema Nervoso Central , Educação Física e Treinamento
7.
Rev. bras. ciênc. esporte ; 41(1): 59-65, jan.-mar. 2019.
Artigo em Português | LILACS-Express | ID: biblio-990598

RESUMO

Resumo Provas cíclicas de longa duração exigem que atletas tomem decisões acerca do uso de energia durante a prova. Visto isso, diferentes estratégias de ritmo (pacing strategy) foram diagnosticadas a fim de promover uma economia de energia durante o esforço. Portanto, o objetivo desta revisão é apresentar os principais mecanismos da estratégia de ritmo, baseados nos modelos de tomada de decisão sustentados por informações aferentes ou contextuais/intuitivas, que são usadas para calcular e reduzir um possível risco de fadiga prematura durante uma tarefa de endurance.


Abstract Long cyclic exercises require that athletes make decisions about the use of energy during the trial, as this, different pacing strategies were diagnosed in order to promote an economy of energy during exercise. Therefore the aim of this review was to present the major exercise strategy mechanisms, based on the decision-making models supported by accurate afferent information, or contextual / intuitive, which are used to calculate the risk of the exercise/test, and decide to reduce/maintain/increase the pace of exercise/test.


Resumen Las pruebas cíclicas a largo plazo requieren que los atletas tomen decisiones sobre el uso de la energía durante la carrera. De esta manera, se diagnosticaron diferentes estrategias de ritmos (pacing strategy) con el fin de promover una economía de energía durante el esfuerzo. Por tanto, el objetivo de esta revisión es presentar los principales mecanismos de la estrategia de ritmo, basados en los modelos de toma de decisiones con el apoyo de la información aferente exacta, o contextual/intuitiva, que se utiliza para calcular el posible riesgo de cansancio prematuro durante la prueba de resistencia.

8.
Physiol Behav ; 204: 41-48, 2019 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-30742838

RESUMO

PURPOSE: To verify whether caffeine (CAF) could increase the prefrontal cortex (PFC) activation and improve 20 km cycling time trial (TT20km) performance in mentally fatigued cyclists. METHODS: After preliminary TT20km, twelve recreational cyclists (VO2MAX of 58.9 ±â€¯6.2 mL kg min-1) performed a familiarization with a cognitive test to induce mental fatigue (MF) and psychological scales. Thereafter, they performed: 2) a baseline TT20km; 3) a mentally fatigued TT20km (MF); 4 and 5) a mentally fatigued TT20km after CAF (MF + CAF) or placebo (MF + PLA) ingestion, in a double-blind, counterbalanced design. Performance and psychological responses were obtained throughout the TT20km, while PFC electroencephalography (EEG) theta wave was obtained before and after the mental fatigue test. RESULTS: The mental fatigue-induced increase in EEG theta wave (↑ ~ 4.8%) was reverted with CAF (↓ 8.8%) and PLA ingestion (↓ 4.8%). CAF improved TT20km performance in mentally fatigued cyclists by reducing time (p = .00; ↓ ~ 1.7%) and increasing WMEAN (p = .00; ↑ ~ 3.6%), when compared to MF + PLA. The RPE-power output ratio was lower (p = .01), but affect (p = .018), motivation (p = .033) and emotional arousal (p = .001) were greater throughout the TT20km in MF + CAF than in MF + PLA. CONCLUSIONS: CAF ingestion improved TT20km performance and psychological responses in mentally fatigued cyclists, despite the unaltered PFC activation.

12.
Sports Med ; 49(1): 57-66, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30488186

RESUMO

BACKGROUND: Despite the growing number of studies reporting carbohydrate mouth rinse effects on endurance performance, no systematic and meta-analysis review has been conducted to elucidate the level of evidence of carbohydrate mouth rinse effects on cycling trial performance such as time-, work-, and distance-based trials. OBJECTIVES: The objective of this study were to establish the effect of a carbohydrate mouth rinse on cycling performance outcomes such as mean power output and time to complete a trial, together with the risk of bias in the cycling-carbohydrate mouth rinse literature. METHODS: We systematically reviewed randomized placebo-controlled trials that assessed carbohydrate mouth rinse effects on mean power output and time to complete the trial. A random-effects meta-analysis assessed the standardized mean difference between carbohydrate and placebo mouth rinses. RESULTS: Thirteen studies (16 trials) were qualitatively (systematic review) and quantitatively (meta-analysis) analyzed with regard to mean power output (n = 175) and time to complete the trial (n = 151). Overall, the reviewed studies showed a low risk of bias and homogeneous results for mean power output (I2 = 0%) and time to complete the trial (I2 = 0%). When compared with placebo, the carbohydrate mouth rinse improved mean power output (standardized mean difference = 0.25; 95% confidence interval 0.04-0.46; p = 0.02), but not the time to complete the trial (standardized mean difference = - 0.13; 95% confidence interval - 0.36 to 0.10; p = 0.25). CONCLUSION: The present systematic and meta-analytic review supports the notion that a carbohydrate mouth rinse has the potential to increase mean power output in cycling trials, despite showing no superiority over placebo in improving time to complete the trials.

13.
Motriz (Online) ; 25(2): e101906, 2019. graf
Artigo em Inglês | LILACS-Express | ID: biblio-1012700

RESUMO

Abstract Aim: The aim of the study was to analyze the impact of a based-team sports physical education class on inhibitory control of elementary school children. Methods: Were selected 29 elementary school students (13 boys and 16 girls; 10.7 ± 0.7 years old; 43.2 ± 8.2 kg weight; 147 ± 5 cm height). Participants were submitted to a 50-minute sports-based physical education class performed at moderate intensity. Inhibitory control was measured before and immediately after the end of the physical education class by the Stroop Test. Results: Results indicate that the variables derived from Stroop Test performance overall reaction time were significantly reduced after the physical education class (p < 0.05). Conclusion: These results suggest that a 50-minute sports-based physical education class performed at moderate intensity elicited a significant improvement on the inhibitory control elementary school students.

14.
PLoS One ; 13(6): e0197124, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29874256

RESUMO

Previous studies investigating the effects of high intensity interval training (HIIT) and moderate intensity continuous training (MICT) showed controversial results. The aim of the present study was to systematically review the literature on the effects of HIIT and MICT on affective and enjoyment responses. The PRISMA Statement and the Cochrane recommendation were used to perform this systematic review and the database search was performed using PubMed, Scopus, ISI Web of Knowledge, PsycINFO, and SPORTDiscus. Eight studies investigating the acute affective and enjoyment responses on HIIT and MICT were included in the present systematic review. The standardized mean difference (SMD) was calculated for Feeling Scale (FS), Physical Activity Enjoyment Scale (PACES) and Exercise Enjoyment Scale (EES). The MICT was used as the reference condition. The overall results showed similar beneficial effects of HIIT on PACES and EES responses compared to MICT with SMDs classified as small (PACES-SMD = 0.49, I2 = 69.3%, p = 0.001; EES-SMD = 0.48, I2 = 24.1%, p = 0.245) while for FS, the overall result showed a trivial effect (FS-SMD = 0.19, I2 = 78.9%, p<0.001). Most of the comparisons performed presented positive effects for HIIT. For the FS, six of 12 comparisons showed beneficial effects for HIIT involving normal weight and overweight-to-obese populations. For PACES, six of 10 comparisons showed beneficial effects for HIIT involving normal weight and overweight-to-obese populations. For EES, six of seven comparisons showed beneficial effects for HIIT also involving normal weight and overweight-to-obese populations. Based on the results of the present study, it is possible to conclude that HIIT exercise may be a viable strategy for obtaining positive psychological responses. Although HIIT exercise may be recommended for obtaining positive psychological responses, chronic studies should clarify the applicability of HIIT for exercise adherence.


Assuntos
Condicionamento Físico Humano , Feminino , Humanos , Masculino
15.
BMJ Open Sport Exerc Med ; 4(1): e000353, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29629188

RESUMO

Dr Robergs suggested that the central governor model (CGM) is not a well-worded theory, as it deviated from the tenant of falsification criteria. According to his view of science, exercise researches with the intent to prove rather than disprove the theory contribute little to new knowledge and condemn the theory to the label of pseudoscience. However, exercise scientists should be aware of limitations of the falsification criteria. First, the number of potential falsifiers for a given hypothesis is always infinite so that there is no mean to ensure asymmetric comparison between theories. Thus, assuming a competition between CGM and dichotomised central versus peripheral fatigue theories, scientists guided by the falsification principle should know, a priori, all possible falsifiers between these two theories in order to choose the finest one, thereby leading to an oversimplification of the theories. Second, the failure to formulate refutable hypothesis may be a simple consequence of the lack of instruments to make crucial measurements. The use of refutation principles to test the CGM theory requires capable technology for online feedback and feedforward measures integrated in the central nervous system, in a real-time exercise. Consequently, falsification principle is currently impracticable to test CGM theory. The falsification principle must be applied with equilibrium, as we should do with positive induction process, otherwise Popperian philosophy will be incompatible with the actual practice in science. Rather than driving the scientific debate on a biased single view of science, researchers in the field of exercise sciences may benefit more from different views of science.

16.
Arch Cardiol Mex ; 88(5): 413-422, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-29496407

RESUMO

OBJECTIVE: The present study aimed to investigate the effects of a 6-month multicomponent exercise program on blood pressure, heart rate, and double product of uncontrolled and controlled normotensive and hypertensive older patients. METHODS: The study included 183 subjects, 97 normotensives, of which 53 were controlled normotensives (CNS), and 44 uncontrolled normotensives (UNS), as well as 86 hypertensives, of which 43 were controlled hypertensives (CHS), and 43 uncontrolled hypertensives (UHS). Volunteers were recruited and blood pressure and heart rate measurements were made before and after a 6-month multicomponent exercise program. The program of physical exercise was performed twice a week for 26 weeks. The physical exercises program was based on functional and walking exercises. Exercise sessions were performed at moderate intensity. RESULTS: The results indicated that UHS showed a marked decrease in systolic (-8.0mmHg), diastolic (-11.1mmHg), mean (-10.1mmHg), and pulse pressures, heart rate (-6.8bpm), and double product (-1640bpmmmHg), when compared to baseline. Similarly, diastolic (-5.5mmHg) and mean arterial (-4.8mmHg) pressures were significantly decreased in UNS. Concomitantly, significant changes could be observed in the body mass index (-0.9kg/m2; -1.5kg/m2) and waist circumference (-3.3cm; only UHS) of UNS and UHS, which may be associated with the changes observed in blood pressure. CONCLUSIONS: In conclusion, the data of the present study indicate that a 6-month multicomponent exercise program may lead to significant reductions in blood pressure, heart rate, and double product of normotensive and hypertensive patients with high blood pressure values.


Assuntos
Pressão Sanguínea/fisiologia , Terapia por Exercício/métodos , Frequência Cardíaca/fisiologia , Hipertensão/terapia , Idoso , Índice de Massa Corporal , Feminino , Humanos , Hipertensão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Fatores de Tempo , Circunferência da Cintura/fisiologia
18.
Int J Sports Physiol Perform ; 13(2): 208-213, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-28605210

RESUMO

Cross-country mountain biking (XCO) is a popular high-intensity endurance cycling event, but XCO pacing strategy has not been fully examined. This study examined the pacing strategies of different XCO athletes during a laboratory-simulated XCO performance test. Brazilian cyclists classified as performance-cohort level 3 performed an XCO race simulation. The simulation consisted of four 10-km laps with a gradient of 0-10%. No group-vs-time interaction was found in lap time (P = .169), absolute (P = .719) and relative (P = .607) power output, ratings of perceived exertion (P = .182), or heart rate (P = .125). There was a time main effect, as athletes decreased power output by 0.3 W/kg throughout the XCO simulation, thereby resulting in a 1.6-min decrement per lap. The power output corresponding to the onset of blood lactate accumulation adequately represented the mean power of the first lap. These results showed that 2 groups of cyclists with different training status adopted similar pacing strategies during an XCO race simulation, as they both used a fast-starting pacing strategy followed by positive pacing that resulted in a linear decrease in power output at every lap.


Assuntos
Ciclismo/fisiologia , Resistência Física/fisiologia , Adulto , Antropometria , Brasil , Teste de Esforço , Frequência Cardíaca/fisiologia , Humanos , Ácido Láctico/sangue , Masculino , Percepção/fisiologia , Esforço Físico/fisiologia
19.
J. Phys. Educ. (Maringá) ; 29: e2915, 2018.
Artigo em Inglês | LILACS | ID: biblio-893605

RESUMO

ABSTRACT The origin of fatigue has been the focus of studies involved in sports performance, due to the necessity to clarify the mechanistic bases for the reduced capacity to perform considerable effort intensities. According to the traditional conception of fatigue, mechanisms may encompass peripheral and central sites of fatigue. Peripheral fatigue is understood as events related to an inefficient tissue oxygen delivery, metabolic accumulation, muscular acidosis and muscle substrate depletion. In contrast, the central fatigue is mostly related to events in the central nervous system (CNS) that may involve neurotransmitters changes, altered metabolic profile and elevated temperature. Therefore, the current review aimed to discuss the peripheral and central mechanisms of fatigue, thus driving interpretations of the phenomenon.


RESUMO A etiologia da fadiga tem sido objeto de estudo em pesquisas relacionadas ao desempenho esportivo em função da necessidade de esclarecer os mecanismos que reduzem a capacidade de manutenção do desempenho em intensidades elevadas de esforço. A concepção tradicional de fadiga assume que os mecanismos possam ser desencadeados em sítios de ação central ou periférica. A fadiga periférica é compreendida como uma oferta inadequada de oxigênio tecidual, acúmulo de metabólitos e depleção de substrato energético acelerando a acidose muscular. A fadiga central, por sua vez, oriunda do sistema nervoso central (SNC), apresenta alterações nos neurotransmissores, podendo alterar o perfil metabólico e temperatura do SNC. Desta forma, a presente revisão tem como intuito abordar os mecanismos de fadiga central e periférica, norteando futuras interpretações sobre o fenômeno.


Assuntos
Exercício , Glicogênio Fosforilase Muscular , Fadiga Muscular , Oxigênio
20.
Nutr Health ; 23(4): 231-238, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29214920

RESUMO

BACKGROUND: Ergogenic effects of caffeine (CAF) ingestion have been observed in different cycling exercise modes, and have been associated with alterations in ratings of perceived exertion (RPE). However, there has been little investigation of maximal oxygen uptake (VO2MAX) test outcomes. AIM: This study aimed to verify whether CAF may reduce RPE, thereby improving maximal incremental test (MIT) outcomes such as VO2MAX, time to exhaustion and peak power output (WPEAK). METHODS: Nine healthy individuals performed three MITs (25 W/min until exhaustion) in a random, counterbalanced fashion after ingestion of CAF, placebo perceived as caffeine (PLA), and no supplementation (baseline control). VO2 was measured throughout the test, while RPE was rated according to overall and leg effort sensations. The power output corresponding to submaximal (RPE = 14 according to the 6-20 Borg scale) and maximal RPE was recorded for both overall (O-RPE14 and O-RPEMAX) and leg RPE (L-RPE14 and L-RPEMAX). RESULTS: VO2MAX did not change significantly between MITs; however, CAF and PLA increased time to exhaustion (↑ ∼18.7% and ∼17.1%, respectively; p < .05) and WPEAK (↑ ∼13.0% and ∼11.8%, respectively; p < .05) when compared with control. When compared with control, CAF ingestion reduced submaximal and maximal overall and leg RPEs, the effect being greater in maximal (likely beneficial in O-RPEMAX and L-RPEMAX) than submaximal RPE (possibly beneficial in O-RPE14 and L-RPE14). Similar results were found when participants ingested PLA. CONCLUSIONS: Compared with control, CAF and PLA improved MIT performance outcomes such as time to exhaustion and WPEAK, without altering VO2MAX values. CAF effects were attributed to placebo.


Assuntos
Desempenho Atlético , Cafeína/uso terapêutico , Suplementos Nutricionais , Fadiga/prevenção & controle , Consumo de Oxigênio , Substâncias para Melhoria do Desempenho/uso terapêutico , Esforço Físico , Adulto , Atitude Frente a Saúde , Ciclismo , Cafeína/efeitos adversos , Estimulantes do Sistema Nervoso Central/efeitos adversos , Estimulantes do Sistema Nervoso Central/uso terapêutico , Decepção , Suplementos Nutricionais/efeitos adversos , Fadiga/etiologia , Fadiga/fisiopatologia , Humanos , Perna (Membro) , Dor Musculoesquelética/etiologia , Dor Musculoesquelética/prevenção & controle , Substâncias para Melhoria do Desempenho/efeitos adversos , Reprodutibilidade dos Testes , Índice de Gravidade de Doença , Método Simples-Cego , Fatores de Tempo , Adulto Jovem
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